Heretofore, a box-type furnace the inner wall of which is lined with fire brick has been employed as a steam reforming furnace. Reaction tubes with catalyst have been arranged in the furnace and to these tubes a charge gas is fed and reaction proceeds by heating the gas with a burner attached to the furnace wall.
On the other hand, practical use of plants which utilize nuclear energy as the energy source has been planned in a power generation and in a steelmaking. For realization of the plan, it is very desirable from the viewpoint of thermal efficiency to utilize a high temperature heating medium such as helium gas from a nulear plant as thermal energy for chemical industries.
From the above viewpoint, we have considered utilizing high temperature helium gas from a nuclear plant as the source of thermal energy for steam reforming which requires high temperatures, and have achieved the present invention by developing a reforming reactor useful for this object. Other high temperature gases can be utilized in the present invention as well as high temperature helium gas from a nuclear reactor and thus, this invention is very profitable.